gclient: fetch arbitrary refs

Bug: 624178
Change-Id: I7ffbf58441e8762630c3beec642108bcc671aae6
Reviewed-on: https://chromium-review.googlesource.com/647848
Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Paweł Hajdan Jr. <phajdan.jr@chromium.org>

gclient_scm.py

@@ -543,6 +543,8 @@ class GitWrapper(SCMWrapper):
 
     self._UpdateBranchHeads(options, fetch=True)
 
+    revision = self._AutoFetchRef(options, revision)
+
     # This is a big hammer, debatable if it should even be here...
     if options.force or options.reset:
       target = 'HEAD'
@@ -919,6 +921,7 @@ class GitWrapper(SCMWrapper):
       if template_dir:
         gclient_utils.rmtree(template_dir)
     self._UpdateBranchHeads(options, fetch=True)
+    revision = self._AutoFetchRef(options, revision)
     remote_ref = scm.GIT.RefToRemoteRef(revision, self.remote)
     self._Checkout(options, ''.join(remote_ref or revision), quiet=True)
     if self._GetCurrentBranch() is None:
@@ -1148,12 +1151,15 @@ class GitWrapper(SCMWrapper):
     checkout_args.append(ref)
     return self._Capture(checkout_args)
 
-  def _Fetch(self, options, remote=None, prune=False, quiet=False):
+  def _Fetch(self, options, remote=None, prune=False, quiet=False,
+             refspec=None):
     cfg = gclient_utils.DefaultIndexPackConfig(self.url)
     fetch_cmd =  cfg + [
         'fetch',
         remote or self.remote,
     ]
+    if refspec:
+      fetch_cmd.append(refspec)
 
     if prune:
       fetch_cmd.append('--prune')
@@ -1185,6 +1191,17 @@ class GitWrapper(SCMWrapper):
     if fetch and need_fetch:
       self._Fetch(options, prune=options.force)
 
+  def _AutoFetchRef(self, options, revision):
+    """Attempts to fetch |revision| if not available in local repo.
+
+    Returns possibly updated revision."""
+    try:
+      self._Capture(['rev-parse', revision])
+    except subprocess2.CalledProcessError:
+      self._Fetch(options, refspec=revision)
+      revision = self._Capture(['rev-parse', 'FETCH_HEAD'])
+    return revision
+
   def _Run(self, args, options, show_header=True, **kwargs):
     # Disable 'unused options' warning | pylint: disable=unused-argument
     kwargs.setdefault('cwd', self.checkout_path)

testing_support/fake_repos.py

@@ -281,6 +281,12 @@ class FakeReposBase(object):
       new_tree = tree.copy()
     self.git_hashes[repo].append((commit_hash, new_tree))
 
+  def _fast_import_git(self, repo, data):
+    repo_root = join(self.git_root, repo)
+    logging.debug('%s: fast-import %s', repo, data)
+    subprocess2.check_call(
+        ['git', 'fast-import', '--quiet'], cwd=repo_root, stdin=data)
+
   def check_port_is_free(self, port):
     sock = socket.socket()
     try:
@@ -298,7 +304,7 @@ class FakeReposBase(object):
 
 class FakeRepos(FakeReposBase):
   """Implements populateGit()."""
-  NB_GIT_REPOS = 12
+  NB_GIT_REPOS = 13
 
   def populateGit(self):
     # Testing:
@@ -620,6 +626,43 @@ deps = {
       'origin': 'git/repo_12@1\n',
     })
 
+    self._fast_import_git('repo_12', """blob
+mark :1
+data 6
+Hello
+
+blob
+mark :2
+data 4
+Bye
+
+reset refs/changes/1212
+commit refs/changes/1212
+mark :3
+author Bob <bob@example.com> 1253744361 -0700
+committer Bob <bob@example.com> 1253744361 -0700
+data 8
+A and B
+M 100644 :1 a
+M 100644 :2 b
+""")
+
+    self._commit_git('repo_13', {
+      'DEPS': """
+deps = {
+  'src/repo12': '/repo_12',
+}""",
+      'origin': 'git/repo_13@1\n',
+    })
+
+    self._commit_git('repo_13', {
+      'DEPS': """
+deps = {
+  'src/repo12': '/repo_12@refs/changes/1212',
+}""",
+      'origin': 'git/repo_13@2\n',
+    })
+
 
 class FakeRepoSkiaDEPS(FakeReposBase):
   """Simulates the Skia DEPS transition in Chrome."""

tests/gclient_scm_test.py

@@ -792,8 +792,11 @@ class UnmanagedGitWrapperTestCase(BaseGitWrapperTestCase):
     self.assertEquals(file_list, expected_file_list)
     self.assertEquals(scm.revinfo(options, (), None),
                       '9a51244740b25fa2ded5252ca00a3178d3f665a9')
-    self.assertEquals(self.getCurrentBranch(), 'feature')
-    self.checkNotInStdout('Checked out feature to a detached HEAD')
+    # indicates detached HEAD
+    self.assertEquals(self.getCurrentBranch(), None)
+    self.checkInStdout(
+        'Checked out 9a51244740b25fa2ded5252ca00a3178d3f665a9 '
+        'to a detached HEAD')
 
     rmtree(origin_root_dir)
 

tests/gclient_smoketest.py

@@ -439,6 +439,36 @@ class GClientSmokeGIT(GClientSmokeBase):
     ])
     self.assertTree(tree)
 
+  def testSyncFetch(self):
+    if not self.enabled:
+      return
+    self.gclient(['config', self.git_base + 'repo_13', '--name', 'src'])
+    _out, _err, rc = self.gclient(['sync', '-v', '-v', '-v'])
+    self.assertEquals(0, rc)
+
+  def testSyncFetchUpdate(self):
+    if not self.enabled:
+      return
+    self.gclient(['config', self.git_base + 'repo_13', '--name', 'src'])
+
+    # Sync to an earlier revision first, one that doesn't refer to
+    # non-standard refs.
+    _out, _err, rc = self.gclient(
+        ['sync', '-v', '-v', '-v', '--revision', self.githash('repo_13', 1)])
+    self.assertEquals(0, rc)
+
+    # Make sure update that pulls a non-standard ref works.
+    _out, _err, rc = self.gclient(['sync', '-v', '-v', '-v'])
+    self.assertEquals(0, rc)
+
+  def testSyncDirect(self):
+    if not self.enabled:
+      return
+    self.gclient(['config', self.git_base + 'repo_12', '--name', 'src'])
+    _out, _err, rc = self.gclient(
+        ['sync', '-v', '-v', '-v', '--revision', 'refs/changes/1212'])
+    self.assertEquals(0, rc)
+
   def testRunHooks(self):
     if not self.enabled:
       return